Donald J. Trump said in an interview published on Sunday that he would be in favor of Britain leaving the European Union.

Mr. Trump made the remarks in an interview with The Sunday Times of London ahead of a referendum on the issue on Thursday and before his planned visit to Britain.

“I would personally be more inclined to leave, for a lot of reasons like having a lot less bureaucracy,” Mr. Trump said. “But I am not a British citizen. This is just my opinion.”

Mr. Trump has previously suggested that Britain “should leave,” although he has offered only circumscribed thoughts about the issue, which is expected to affect global markets.

Mr. Trump is expected to arrive in Scotland on Friday, a day after the vote, for a ribbon-cutting at one of his newest golf clubs. It will be his first international trip since he became the presumptive Republican nominee.

Prime Minister David Cameron of Britain, who is urging Britons to vote to stay in the European Union, has been deeply critical of Mr. Trump, describing him as “divisive.” The newly elected mayor of London, Sadiq Khan, the city’s first Muslim mayor, has also criticized Mr. Trump for his proposed ban on Muslim immigrants entering the United States.

In the Times of London interview, Mr. Trump declined to say anything about Mr. Khan other than wishing him luck. And he struck a magnanimous note about Mr. Cameron.

“I respect David Cameron,” Mr. Trump said. “He doesn’t know me, but I respect him. I respect what he has done and what he is doing, and I would imagine we will have a very good relationship if I am successful.”

Mr. Trump said he favored maintaining the “special relationship” between Britain and the United States that has existed for decades. But in a tweak at Tony Blair, the former British prime minister, Mr. Trump added, “Sometimes the special relationship hasn’t worked out too well where they made a common mistake like Iraq. Frankly, they would have been a lot better off had they not become involved with Iraq.”

A spokeswoman for Mr. Trump did not respond on Sunday evening to an email seeking comment.